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After a season when sugar beet crops were ravaged by virus yellows, growers will be doing everything possible to help speed growth and propel crops towards adult plant resistance. Good herbicide timing will be crucial if crops are to avoid being hindered in their development.

“Recent conversations about sugar beet have been dominated by virus yellows. This is understandable, but it shouldn’t distract from the need to consider weed control without desmedipham,” says David Allison, Frontier Agriculture sugar beet crop protection specialist.

“For more than a generation, the likes of Betanal maxxPro and other desmedipham-containing products made weed control easy. These products delivered a broad-spectrum of activity and high crop safety.  Without desmedipham weed control at the pre-emergence stage will need to be better and the first post-emergence application delayed until the crop is at the expanded cotyledon stage, this may involve more regular inspections if the spray is to be well timed,” he adds.

Although strategies will need to evolve in response, growers should not despair.

“It is important to consider how programmes can be adapted to avoid placing undue pressure on phenmedipham and ethofumesate. On land known to harbour a high weed burden, a pre-drilling application of Roundup (glyphosate) may be the best policy while a robust residual will almost certainly be necessary to provide control through until the first post-em spray can be applied,” says Mr Allison.

For some growers there will be the temptation to return to straights, but the workload these exert on the sprayer operator mean this is unlikely to be the favoured approach of many. For those who prefer the convenience of a formulated product, there is Betanal Tandem (phenmedipham + ethofumesate).

“Betanal Tandem performs strongly against a broad range of weeds and its formulation is safe to the crop, but in many situations, it will need a residual such as metamitron to bolster control,” he says.

Betanal Tandem + Mero gives excellent weed control and can be bolstered with metamitron (% control achieved)

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Source: Bayer. 8 trials - AUT, BEL, CZE, DEU, FRA, GBR – assessed 4-6 weeks after application.
Programmes consisted of three treatments: Betanal Tandem: 1.0 L/ha; 1.5 L/ha; 1.5 L/ha. Where Goltix and Mero were applied it was at 1.25 L/ha and 1 L/ha respectively.

Advantages of the Conviso Smart system

While Betanal Tandem will be valuable to those in need of a standard approach to weed control, there is an alternative system available for best crop safety, with highly efficient and convenient weed control, due to less mixtures and more time saved. 

In 2020 the introduction of varieties tolerant to the acetolactate synthase (ALS) group of herbicides introduced a new system under the brand ‘Conviso® Smart’. It promised to simplify weed control while expanding the range of weed species that could be reliably controlled.

“The loss of desmedipham is perhaps the catalyst needed for growers to take a closer look at what Conviso® Smart has to offer. It certainly adds to control but in some situations should not be used in isolation. In my experience the Conviso® One herbicide fits best after an application of a classic herbicides of both a residual and contact nature,” he says. 

Part of the appeal of the Conviso® Smart system is the opportunity it presents to reduce the number of herbicide applications needed to achieve weed control. It is the intention of the system, that growers should be able to achieve a desired level of weed control with a single application of Conviso One (foramsulfuron + thiencarbazone-methyl) although in some situations and depending on the weed spectrum to be controlled post-emergence applications of Betanal Tandem may be needed to supplement control.
 

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The broadleaved weed control performance of Conviso One is close to that achieved with Betanal maxxPro

Source: Bayer; 53 trials, 2012-14

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The Conviso One herbicide offers unparalleled control of grassweeds
Source: Bayer; 53 trials, 2012-14

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